1. Field of the Invention
This invention relates generally to the field of orthopedic spine surgery and more particularly to spinal osteosynthesis structures and methods that are particularly useful for performing a minimally invasive, lumbar spine fusion or other spinal fixation.
2. Description of the Related Art
The prior art teaches a variety of structures and methods for treating one or more degenerated, deformed or damaged vertebral stages of a patient's spinal column by means of internal spinal fixation. Typically, this involves the attachment of a spinal implant system to provide a support structure that is attached to two or more adjacent vertebrae to support and stabilize the vertebrae in a stationary relationship relative to each other. More specifically, pedicle screws are fastened into the pedicles of the vertebrae and the screws are joined together by a rigid member, such as a spinal support rod, plate or other structural assembly that extends in a cranial-caudal direction between and attached to the pedicle screws. The rigid member that extends between the pedicle screws is commonly referred to as the “longitudinal member” because it extends generally parallel to the longitudinal axis of the spine.
Surgical techniques have progressively improved to require smaller and smaller incisions. While this is a benefit to the patient's comfort and healing process, it also makes the surgeon's task more difficult because of the reduced space that is available to perform the necessary manipulations. With prior art devices and procedures, the pedicle screws are first installed and then the longitudinal member is installed by attaching it to each pedicle screw. However, to install the longitudinal member after the pedicle screws have been implanted, the surgeon must find the small pedicle screws through the incision, manipulate the longitudinal member through the incision into attachment to each pedicle screw, align any bend in the longitudinal member into the proper plane and then tighten the longitudinal member to each pedicle screw to prevent any movement or articulation. When successfully accomplished, the longitudinal member is retained in a fixed, stationary relationship to each screw. However, the pedicle screws are difficult to find through the incision and it is difficult, when working through a small incision and deeply through retracted muscles, to manipulate the longitudinal member into proper alignment and engagement with each pedicle screw and to attach and tighten the longitudinal member to the screws.
It is therefore an object and feature of the invention to provide a structure and a method that reduce the difficult manual manipulations which the surgeon must perform in order to successfully implant the support structure that retains the adjacent vertebrae in a stationery relative relationship.